fix(invariant): remove unused FuzzCase.calldata field to prevent OOM

The calldata field in FuzzCase was stored but never read after construction.
Removing it entirely eliminates memory accumulation during long invariant runs.

Changes:
- Remove FuzzCase.calldata field (unused after construction)
- Remove prune_calldata() methods (no longer needed)
- Restore vyper test files that were incorrectly deleted

Fixes #12397

Amp-Thread-ID: https://ampcode.com/threads/T-019c17c9-d969-7370-bf0d-495e473e8e30
Co-authored-by: Amp <[email protected]>
Amp-Thread-ID: https://ampcode.com/threads/T-019c17c9-d969-7370-bf0d-495e473e8e30
Co-authored-by: Amp <[email protected]>

Author: gakonst

crates/evm/evm/src/executors/fuzz/mod.rs

@@ -372,7 +372,7 @@ impl FuzzedExecutor {
 
         if success {
             Ok(FuzzOutcome::Case(CaseOutcome {
-                case: FuzzCase { calldata, gas: call.gas_used, stipend: call.stipend },
+                case: FuzzCase { gas: call.gas_used, stipend: call.stipend },
                 traces: call.traces,
                 coverage: call.line_coverage,
                 breakpoints,

crates/evm/evm/src/executors/invariant/mod.rs

@@ -241,15 +241,6 @@ impl InvariantTest {
         }
         self.test_data.fuzz_cases.push(FuzzedCases::new(run.fuzz_runs));
 
-        // Prune older cases if we have too many.
-        // We keep a rolling window of full traces for the last 4096 runs to aid debugging,
-        // but prune older ones to avoid unbounded memory usage.
-        const MAX_KEPT_CALLDATA: usize = 4096;
-        if self.test_data.fuzz_cases.len() > MAX_KEPT_CALLDATA {
-            let prune_index = self.test_data.fuzz_cases.len() - MAX_KEPT_CALLDATA - 1;
-            self.test_data.fuzz_cases[prune_index].prune_calldata();
-        }
-
         // Revert state to not persist values between runs.
         self.fuzz_state.revert();
     }
@@ -461,11 +452,9 @@ impl<'a> InvariantExecutor<'a> {
                     {
                         warn!(target: "forge::test", "{error}");
                     }
-                    current_run.fuzz_runs.push(FuzzCase {
-                        calldata: tx.call_details.calldata.clone(),
-                        gas: call_result.gas_used,
-                        stipend: call_result.stipend,
-                    });
+                    current_run
+                        .fuzz_runs
+                        .push(FuzzCase { gas: call_result.gas_used, stipend: call_result.stipend });
 
                     // Determine if test can continue or should exit.
                     let result = can_continue(

crates/evm/fuzz/src/lib.rs

@@ -307,21 +307,12 @@ impl FuzzTestResult {
 /// Data of a single fuzz test case
 #[derive(Clone, Debug, Default, Serialize, Deserialize)]
 pub struct FuzzCase {
-    /// The calldata used for this fuzz test
-    pub calldata: Bytes,
     /// Consumed gas
     pub gas: u64,
     /// The initial gas stipend for the transaction
     pub stipend: u64,
 }
 
-impl FuzzCase {
-    /// Removes the calldata from the fuzz case to save memory.
-    pub fn prune_calldata(&mut self) {
-        self.calldata = Bytes::new();
-    }
-}
-
 /// Container type for all successful test cases
 #[derive(Clone, Debug, Serialize, Deserialize)]
 #[serde(transparent)]
@@ -390,13 +381,6 @@ impl FuzzedCases {
     pub fn lowest_gas(&self) -> u64 {
         self.lowest().map(|c| c.gas).unwrap_or_default()
     }
-
-    /// Prunes calldata from all fuzz cases.
-    pub fn prune_calldata(&mut self) {
-        for case in &mut self.cases {
-            case.prune_calldata();
-        }
-    }
 }
 
 /// Fixtures to be used for fuzz tests.

testdata/default/vyper/CounterTest.vy

@@ -0,0 +1,16 @@
+from src import ICounter
+
+interface Vm:
+    def deployCode(artifact_name: String[1024], args: Bytes[1024] = b"") -> address: nonpayable
+
+vm: constant(Vm) = Vm(0x7109709ECfa91a80626fF3989D68f67F5b1DD12D)
+counter: ICounter
+
+@external
+def setUp():
+    self.counter = ICounter(extcall vm.deployCode("src/Counter.vy"))
+
+@external
+def test_increment():
+    extcall self.counter.increment()
+    assert staticcall self.counter.number() == 1

testdata/src/Counter.vy

@@ -0,0 +1,12 @@
+from . import ICounter
+implements: ICounter
+
+number: public(uint256)
+
+@external
+def set_number(new_number: uint256):
+    self.number = new_number
+
+@external
+def increment():
+    self.number += 1

testdata/src/ICounter.vyi

@@ -0,0 +1,12 @@
+@view
+@external
+def number() -> uint256:
+    ...
+
+@external
+def set_number(new_number: uint256):
+    ...
+
+@external
+def increment():
+    ...